Effects of Laminar-Turbulent Transition on the Shock-Wave/Boundary-Layer Interaction

This paper presents results of experimental investigations of the nominally 2-D impinging shock-wave interaction with the transitional boundary layer developing on a flat plate at Mach 6 flow conditions. Experiments were conducted in the Ludwieg-Tube Facility at DLR Göttingen using quantitative infrared-thermography, high-speed shadowgraphy and free-stream Pitot-pressure fluctuation measurements. Natural-transition and shockimpingement locations on the flat plate were varied independently in order to establish different initial boundary-layer conditions at the interaction region. The results demonstrate significant impact of these mutual positions on the induced flow topology and on the heat-flux distribution. A range of CFD-validation test cases was created representing transition phenomena in some details. The distribution of the normalized Stanton number, generalized in the present work for a wide range of unit Reynolds numbers, indicate a clear narrow maximum inside the transition region

Development of a rapid inviscid-boundary layer aerodynamics tool

Hypersonic vehicles, combined with scramjet propulsion, offer significant and unique flexibility, performance and reusability benefits over rockets. These characteristics will likely reduce the cost of access-to-space. However, the realisation of such vehicles is significantly complicated by engine performance requirements which dictate relatively low altitude, high dynamic pressure trajectories. The thick atmosphere and high velocities result in high aerodynamic drag and heating. This paper introduces a simple, aerothermodynamic model for the analysis of hypersonic vehicles using Cart3D to calculate the inviscid flow-field and provide edge conditions to boundary layer calculations. Comparisons are made between two viscous methods of varying fidelity; flat plate correlations for skin friction with a simplified running length calculation and integral methods applied along inviscid, surface streamlines. Three validation cases are presented; (1) a hypersonic, blunt body; (2) a delta-wing, lifting body at subsonic to hypersonic Mach numbers and (3) a hypersonic, realistic vehicle configuration with internal flow-paths. In general, Cart3D predicts the lift and pitching moment coefficients well but consistently under-predicts drag given the absence of shear stress. The viscous contribution to aerodynamic forces was found to be adequately modelled using flat plate correlations and a simple Euclidean distance in place of the true running length. Preliminary results, however, suggest predictions of surface heat transfer rates benefit from a streamline running length and higher fidelity boundary layer methods